JP2000335129A - Original plate of direct drawing type lithographic plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make burning-off properties excellent by making a thermosensible layer contain the dyestuff being soluble in a solvent and causing a change in color under laser irradiation. SOLUTION: An organic solvent which dissolves or decomposes uniformly a thermosensible layer composition and most or the whole of which volatilizes by drying after application of the solvent onto a substrate is used for providing a thermosensible layer by coating. Dyestuff used herein causes a change in color under laser irradiation, and one causing no change in color under the laser irradiation does not bring about burning-off properties. As for a mechanism causing the change in color under the laser irradiation, it is preferable that a part of the structure of the dyestuff decomposes to produce gas or a low- molecular compound and causes a change in hue of the dyestuff itself, although the change in color may be caused also by decomposition of the basic structure of the dyestuff. As to the solvent resistance of the thermosensible layer in the part subjected to the laser irradiation, it is preferable that the properties of dissolution in the solvent of the dyestuff having the hue changed are changed from those of the original dyestuff and reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a direct drawing type lithographic printing plate precursor that can be directly made by laser light.
In particular, the present invention relates to a direct drawing type waterless planographic printing plate precursor capable of printing without using dampening solution.

[0002]

2. Description of the Related Art A so-called direct drawing type plate making, in which an offset printing plate is produced directly from an original without using a plate making film, is simple, which does not require skill, rapidity in which a printing plate can be obtained in a short time, Taking advantage of features such as rationality that can be selected from various systems according to quality and cost, the company has begun to enter not only the light printing industry but also the fields of general offset printing and flexographic printing. In particular, a new type of various direct-drawing lithographic printing plates has recently been developed with the rapid progress of output systems such as a prepress system, an image setter, and a laser printer. These direct-drawing lithographic printing plates can be classified according to plate-making methods, such as a method of irradiating a laser beam, a method of writing with a thermal head, a method of partially applying a voltage with a pin electrode, an ink repellent layer or an ink-coated layer by inkjet. And the like. Above all, the method using laser light is resolution,
It is superior to other methods in terms of plate making speed and there are many types.

[0003] The printing plate using the laser light further includes:
There are two types: a photon mode by photoreaction and a heat mode in which photothermal conversion is performed to cause a thermal reaction. In particular, the heat mode method has an advantage that it can be handled in a bright room, and its usefulness has recently been reviewed due to the rapid progress of a semiconductor laser as a light source.

For example, US Pat. No. 5,339,737, US Pat. No. 5,353,705, JP-A-6-55723, US Pat. No. 5,378,580, JP-A-7-1647.
73, JP-A-6-186750, JP-A-7
-309001, JP-A-9-104182, JP-A-9-146264, JP-A-9-146
265, JP-A-9-236927, JP-A-9-244228 and U.S. Pat. No. 5,487,733.
8, US Patent No. 5,385,092, US Patent No. 564
No. 9486, U.S. Pat. No. 5,704,291, and U.S. Pat. No. 5,570,636 describe a direct drawing type waterless planographic printing plate precursor using a laser beam as a light source, a plate making method thereof, and the like.

[0005] The heat-sensitive layer of the printing plate precursor of this thermal destruction method is
Carbon black is mainly used as a laser light absorbing compound, and nitrocellulose is used as a thermal decomposition compound. The carbon black is converted into thermal energy by absorbing laser light, and the heat destroys the heat-sensitive layer. Finally, by removing this portion by development, the silicone rubber layer on the surface is simultaneously peeled off to form an ink-coated portion.

However, in this printing plate, since the image is formed by destroying the heat-sensitive layer, the depth of the cells in the image area becomes deep, and the ink depositing property at minute dots is poor, and the ink mileage is poor. There was a problem. Further, there is also a problem that a crosslinked structure is formed in order to easily cause the heat-sensitive layer to be thermally destroyed, and the printing durability of the printing plate is poor. Furthermore, this printing plate has a problem that the sensitivity is low and a high laser light intensity is required to destroy the heat-sensitive layer.

In Japanese Patent Application Laid-Open No. 9-239943, a laser light is converted into heat to reduce the adhesion to the silicone rubber layer, and the solid content is 10 to 2%.
A heat mode fountain solution-free lithographic printing plate precursor having an addition type silicone rubber layer containing 0% by weight of an organohydrogensiloxane is described. However,
In the same publication, the heat-sensitive layer is basically composed of carbon black and nitrocellulose, is of a type that is removed by laser irradiation and development, and the ink-receiving layer is a primer layer below the heat-sensitive layer. It has a problem of ink mileage and a problem of intensity of laser light required for plate making. Japanese Patent Application Laid-Open No. 9-244228 discloses a technique in which high sensitivity can be attained by including hollow polymer fine particles in a primer layer. However, the problem of ink mileage still remained.

Japanese Unexamined Patent Publication No. 9-239942 discloses a peeling development type printing plate containing a substance which generates an acid in a laser sensitive layer and a polymer compound which is decomposed by the action of an acid. Since two steps, a light irradiation step and a heating step, are required, the steps are complicated, and there is a problem inherent in peeling development that reproducibility of fine halftone dots is poor.

In addition, US Pat. No. 5,379,698, JP-A-7-314934, JP-A-9-236927.
In Japanese Patent Application Laid-Open Publication No. H10-157, a direct drawing type waterless planographic printing plate using a metal thin film as a heat-sensitive layer is described. This printing plate material has a very thin heat-sensitive layer, so that a very sharp image can be obtained, which is advantageous in terms of the resolution of the printing plate. There has been a problem that the heat-sensitive layer at the line portion is peeled off, ink adheres, and becomes a defect on printed matter.

[0010] In order to solve the above-mentioned problems, the silicone rubber layer in the portion irradiated with the laser beam is selectively removed, while the heat-sensitive layer remains, and the heat-peelable direct-drawing waterless lithographic printing is performed. Plates are considered preferred. Although a printing plate in which a heat-sensitive layer remains is obtained by the study of Nichiporenko et al., Since carbon black and thermally decomposable nitrocellulose are used in the heat-sensitive layer, the heat-sensitive layer is sensitive to laser irradiation energy. There were problems such as the instability of the layer remaining and the gas generated by the action of laser irradiation adversely affecting the laser optical system.

In the case of the thermal peeling type, since a very slight reaction is used only in the vicinity of the surface of the heat-sensitive layer, it is difficult to discriminate between the laser beam irradiated portion and the non-irradiated portion by visual observation. There was a problem of inferiority.

[0012]

SUMMARY OF THE INVENTION An object of the present invention is to provide a negative-working, heat-peelable, direct-drawing lithographic printing plate having good print-out properties in order to improve the disadvantages of the prior art. .

[0013]

The direct drawing type lithographic printing plate precursor according to the present invention mainly has the following constitution in order to solve the above-mentioned problems. That is, "a direct drawing type lithographic printing plate precursor having at least a heat-sensitive layer on a substrate, and in the heat-sensitive layer,
A direct-drawing lithographic printing plate precursor characterized in that it contains a dye that is soluble in a solvent and changes color upon laser irradiation. ].

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

A feature of the present invention is that the heat-sensitive layer contains a dye which is soluble in a solvent and which changes its color upon laser irradiation. If the dye used in the present invention is not soluble in a solvent, there is a problem that the dye is not uniformly dispersed at the time of coating the thermosensitive layer.

Examples of the solvent include ordinary organic solvents used for coating the thermosensitive layer. That is, any material can be used as long as it can dissolve or uniformly disperse the heat-sensitive layer composition, can apply the composition on a substrate, and can volatilize all or most of the composition by drying.
Examples of such a solvent include the following specific examples and mixtures thereof.

Ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, alcohols such as methanol, ethanol, propanol, butanol, isopropanol, ethylene glycol derivatives such as ethylene glycol monomethyl ether and ethylene glycol monoethyl ether, and propylene glycol derivatives Ethyl glycol derivatives such as tetrahydrofuran, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, propylene glycol derivatives, ester solvents such as methyl acetate, ethyl acetate, butyl acetate, and ethylene glycol monomethyl ether acetate; Acetic acid, professional Carboxylic acid solvents such as propionic acid,
In addition, dimethylformamide, dimethylacetamide, γ-butyrolactone, N-methylpyrrolidone and the like.

The dye used in the present invention is a dye which changes its color by laser irradiation, and if it does not change its color by laser irradiation, it does not have printability.
Regarding the mechanism that causes color change by laser irradiation,
Although the basic structure of the dye may be decomposed to change the color, it is preferable that a part of the structure of the dye be decomposed to generate a gas or a low molecular compound to change the hue of the dye itself. Examples of gas and low molecular weight compounds generated by decomposition include carbon dioxide gas, nitrogen gas, water, oxygen gas, methane, ethane, propane, 2-methylpropane, butane, 2-methylbutane, 2,2-dimethylbutane, and 2,3. -Dimethylbutane, 2,2,3-
Trimethylbutane, 2,2,3,3-tetramethylbutane, heptane, ethylene, propylene and the like.

Further, it is preferable from the viewpoint of the solvent resistance of the heat-sensitive layer in the laser irradiation part that the solvent solubility of the dye having changed hue changes from that of the original dye and the solubility decreases.

The decomposition temperature of the dye used in the present invention is as follows:
From the storage stability of the printing plate precursor, the drying temperature of the heat-sensitive layer during preparation of the printing plate precursor, and the temperature of the heat-sensitive layer during laser irradiation, the temperature is 100 to 500 ° C, and more preferably 100 to 30 ° C
Preferably it is at 0 ° C.

The dye preferably has a structure represented by the following general formula (I).

[0022]

Embedded image Compounds 1 to 3 can be shown as specific examples of such dyes.

[0023]

Embedded image

[0024]

Embedded image

[0025]

Embedded image

The heat-sensitive layer of the present invention preferably contains a light-to-heat conversion material and a thermosetting compound in addition to the dye.

Examples of the light-to-heat conversion material include black pigments such as carbon black, titanium black, aniline black, and cyanine black; phthalocyanine, naphthalocyanine-based green pigments; carbon graphite; diamine-based metal complexes; dithiol-based metal complexes; Metal complexes, mercaptophenol-based metal complexes, water-containing inorganic compounds, copper sulfate, chromium sulfide, silicate compounds,
Titanium oxide, vanadium oxide, manganese oxide, iron oxide,
Examples include metal oxides such as cobalt oxide and tungsten oxide, and hydroxides and sulfates of these metals. Among these, carbon black is preferred from the viewpoints of light-to-heat conversion rate, economy, and handleability.

In addition, a dye which absorbs infrared rays or near infrared rays, particularly a dye, is preferably used as a photothermal conversion substance. Particularly preferred dyes are cyanine-based, phthalocyanine-based, naphthalocyanine-based, dithiol metal complex-based, piasurenium-based, squarylium-based, croconium-based, azo-based disperse dyes, bisazo-based, bisazostilbene-based, naphthoquinone-based, anthraquinone-based, Examples include perylene, polymethine, indoaniline metal complex dyes, intermolecular CT, benzothiopyran, spiropyran, nigrosine, thioindigo, nitroso, quinoline, and fulgide dyes, particularly dyes.

The content of these light-to-heat converting substances is preferably 1 to 40% by weight, more preferably 5 to 25% by weight, based on the whole heat-sensitive layer composition. When the content is 1% by weight or more, the effect of improving the sensitivity to laser light is large, and when the content is 40% by weight or less, the printing durability of the printing plate does not decrease.

The term "thermosetting compounds" refers to a group of compounds in the heat-sensitive layer of the printing plate precursor, which still have the ability to be cured directly or indirectly by the action of laser irradiation. Say, such as, phenol, cresol, novolak resin and resol resin obtained by the condensation reaction of phenols such as xylenol and formaldehyde, phenol-furfural resin, furan resin, unsaturated polyester, alkyd resin,
Examples include, but are not limited to, urea resins, melamine resins, guanamine resins, epoxy resins, diallyl phthalate resins, unsaturated polyurethane resins, and polyimide precursors.

In addition to the above-mentioned resins which react themselves, a composition obtained by adding a thermo-reactive crosslinking agent to a compound having a reactive functional group is also used in the present invention as a thermosetting compound. be able to. Examples of the crosslinking agent include known polyfunctional compounds having crosslinking properties, such as polyfunctional blocked isocyanate, polyfunctional epoxy compound, polyfunctional acrylate compound, metal chelate compound, polyfunctional aldehyde, polyfunctional mercapto compound, and polyfunctional alkoxy. Examples thereof include a silyl compound, a polyfunctional amine compound, a polyfunctional carboxylic acid, a polyfunctional vinyl compound, a polyfunctional diazonium salt, a polyfunctional azide compound, and hydrazine. Further, a known catalyst may be added to promote the reaction of the crosslinking agent. These crosslinking agents can be used alone or in combination of two or more.

Further, a compound which generates an acid or an amine under the action of heat and a compound which cures under the action of the generated acid or amine can be used in the present invention. Among such thermosetting compounds, a combination of a phenol resin and a metal chelate compound is particularly preferred.

The proportion of such a thermosetting compound in the thermosensitive layer is preferably from 10 to 95% by weight, more preferably from 30 to 70% by weight of the total solids of the thermosensitive layer. When the amount of the thermosetting compound is 10% by weight or more,
The effect of improving the solvent resistance of the heat-sensitive layer in the image area due to the heat curing of the heat-sensitive layer is observed. Does not cause a problem in image forming properties.

In addition, the heat-sensitive layer may contain a binder polymer, a surfactant and various additives.

Specific examples of the binder polymer include acrylic acid esters such as polymethyl methacrylate and polybutyl methacrylate, homopolymers and copolymers of methacrylic acid esters, and styrene monomers such as polystyrene, α-methylstyrene and hydroxystyrene. Homopolymers and copolymers, various synthetic rubbers such as isoprene and styrene-butadiene, homopolymers and copolymers of vinyl esters such as polyvinyl acetate and vinyl chloride, and polyoxides such as polyethylene oxide and polypropylene oxide (Polyethers), polyesters, polyurethanes, polyamides, cellulose derivatives such as ethyl cellulose, cellulose acetate, phenoxy resin, methylpentene resin, polyparaxylylene resin, poly Such as E two-sulfide resin, and the like.

The content of these binders is preferably 5 to 70% by weight based on the total heat-sensitive layer composition,
% Is more preferred. When the content is 5% or more, there is no problem in printing durability and coating properties of the coating solution, and when the content is 70% by weight or less, there is no adverse effect on image reproducibility.

The thickness of the heat-sensitive layer is 0.1 to 1 in terms of the coating layer.
0 g / m ² is preferable in terms of printing durability of the printing plate and excellent productivity because the diluting solvent is easily evaporated, and 1 to 5 g / m ^2.
Is more preferred.

Further, the printing plate precursor of the present invention preferably has an ink repellent layer. Examples of the ink repellent layer include a hydrophilic layer made of vinyl alcohols, a hydrophilic layer containing acrylic acid or acrylate, sulfonic acid or sulfonic acid salt, JP-A-8-282142, and JP-A-8-282.
No. 82144, JP-A-8-292558, JP-A-9-54425, and the like, a hydrophilic swelling layer, a silicone rubber layer, a layer containing a fluorine compound, and the like, which can be used, are preferred. Is a silicone rubber layer. As the silicone rubber layer, any of an addition polymerization type and a condensation polymerization type can be used.

As the components constituting the addition polymerization type silicone rubber layer, vinyl group-containing polydimethylsiloxane,
It contains a SiH group-containing polysiloxane, a reaction inhibitor for the purpose of controlling the curing rate, and a curing catalyst.

The vinyl group-containing polydimethylsiloxane is
It has a structure represented by the following general formula (II) and has a vinyl group at a molecular terminal and / or in a main chain.

[0041]

Embedded image (In the formula, n represents an integer of 2 or more, and R ¹ and R ^{2 each} have 1 carbon atom.
~ 50 substituted or unsubstituted alkyl groups, having 2 to 2 carbon atoms
50 substituted or unsubstituted alkenyl groups, having 4 to 4 carbon atoms
At least one group selected from the group consisting of 50 substituted or unsubstituted aryl groups, which may be the same or different; ) In the above formula, R ¹ and R ² are all 5
It is preferable that 0% or more is a methyl group from the viewpoint of ink repellency of the printing plate. Further, the molecular weight may be in the range of thousands to hundreds of thousands, but from the viewpoint of handleability, ink repellency and scratch resistance of the obtained printing plate, the weight-average molecular weight is 10,000 to 200,000, and more preferably 3 to 100,000. It is preferable to use a material of 10,000 to 150,000.

Examples of the SiH group-containing polysiloxane include compounds having a SiH group in the molecular chain or at the terminal, such as those represented by the following general formulas (III) to (VI).

[0043]

Embedded image (In the formula, n is an integer of 1 or more.)

[0044]

Embedded image (In the formula, n is an integer of 1 or more.)

[0045]

Embedded image (In the formula, n is an integer of 1 or more, and m is an integer of 1 or more.)

[0046]

Embedded image

S in SiH group-containing polysiloxane
The number of iH groups is 2 or more in one molecule, and more preferably 3 or more.
Preferably, the number is at least. The addition amount of the SiH group-containing polysiloxane is 3% of the total composition of the silicone rubber layer.
The content is preferably from 20 to 20% by weight, more preferably from 5 to 15% by weight. In terms of the molar ratio with respect to polydimethylsiloxane, the molar ratio of SiH group / vinyl group of polydimethylsiloxane is preferably 1.5 to 30, and 10 to 2
0 is more preferred. When the molar ratio is 1.5 or more, the curing of the silicone rubber layer is not insufficient and
If it is 0 or less, the physical properties of the rubber become brittle, and there is no adverse effect on the scratch resistance and the like of the printing plate.

Examples of the reaction inhibitor include a nitrogen-containing compound, a phosphorus-based compound, and an unsaturated alcohol, and an acetylene group-containing alcohol is preferably used.
The preferable addition amount of the reaction inhibitor is 0.01 to 10% by weight, more preferably 1 to 10% by weight in the silicone rubber composition.
~ 5 wt%.

The curing catalyst is a Group III transition metal compound, preferably a platinum compound. Specifically, platinum alone, platinum chloride, chloroplatinic acid, olefin-coordinated platinum, an alcohol-modified complex of platinum, and methyl methyl of platinum A vinyl polysiloxane complex can be given as an example. The amount of such a curing catalyst is 0.01 to 20% by weight as a solid content in the silicone rubber layer, and further 0.1 to 10% by weight.
It is preferred that 0.01wt% of catalyst to be added
In the above case, the curing of the silicone rubber layer becomes sufficient,
Further, there is no problem in adhesion to the heat-sensitive layer. On the other hand, when the content is 20% by weight or less, the pot life of the silicone rubber layer solution is not adversely affected. In terms of the amount of metal such as platinum in the silicone rubber layer composition,
It is preferably from 10 to 1000 ppm, more preferably from 100 to 500 ppm.

In addition to these compositions, known compositions such as a hydroxyl group-containing organopolysiloxane or a hydrolyzable functional group-containing silane or siloxane, which is a composition of the condensation type silicone rubber layer, and silica for the purpose of improving rubber strength. And a known silane coupling agent, titanate-based coupling agent, aluminum-based coupling agent and the like for the purpose of improving the adhesiveness. As the silane coupling agent, alkoxysilanes, acetoxysilanes, ketoximine silanes and the like are preferable, and those having a vinyl group and ketoximine silanes are particularly preferable.

The components constituting the condensation-polymerized silicone rubber layer include a hydroxyl group-containing polydimethylsiloxane, a crosslinking agent (deacetic acid type, deoxime type, dealcohol type, deamine type, deamine type, deacetone type, deamidation type). , Deaminoxy type, etc.), and a curing catalyst.

The hydroxyl group-containing polydimethylsiloxane is also
It has a structure represented by the general formula (I). Hydroxyl group is a molecule
Can be located at the termini and / or in the backbone
However, those preferably used have a hydroxyl group at the molecular weight end.
Is what you do. R in the general formula ¹, R^TwoAbout
The fact that more than 50% of the total is methyl groups
It is preferable in terms of ink repulsion. Thousands to number as molecular weight
100,000 items can be used, but their handling and obtained seals
From the viewpoint of ink repulsion and scratch resistance of the printing plate,
Use those with a child volume of 10,000 to 200,000 and even 30,000 to 150,000
Preferably.

Examples of the crosslinking agent used in the condensation polymerization type silicone rubber layer include acetoxysilanes, alkoxysilanes, ketoximinesilanes, and allyloxysilanes represented by the following general formula (VII). Can be. (R ² ) _4-n SiX _n (VII) (wherein, n represents an integer of 2 to 4, and R ² represents a substituted or unsubstituted alkyl group, alkenyl group, aryl group having 1 or more carbon atoms, or X represents a combined group of
Represents a functional group selected from a halogen atom, an alkoxy group, an acyloxy group, a ketoximine group, an aminooxy group, an amide group, and an alkenyloxy group. ) In the above formula,
The number n of the hydrolyzable groups is preferably 3 or 4.

Specific compounds include methyltriacetoxysilane, ethyltriacetoxysilane, vinyltriacetoxysilane, methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, tetraethoxysilane, tetraethoxysilane Propoxysilane, vinyltrimethoxysilane, vinyltriphenoxysilane, vinyltriethoxysilane,
Allyltriethoxysilane, vinyltriisopropoxysilane, vinyltrisisopropenoxysilane, vinylmethylbis (methylethylketoximine) silane, methyltri (methylethylketoximine) silane, vinyltri (methylethylketoximine) silane, tetra (methylethylketoximine) Examples include, but are not limited to, silane, diisopropenoxydimethylsilane, triisopropenoxymethylsilane, and tetraallyloxysilane. Among these, acetoxysilanes and ketoximinesilanes are preferred from the viewpoints of the curing rate of the silicone rubber layer, handleability, and the like.

The amount of the crosslinking agent represented by the general formula (VI) is 1.5 to 20 wt% of the total composition of the silicone rubber layer.
%, More preferably 3 to 10 wt%. In terms of the molar ratio to polydimethylsiloxane, the molar ratio of functional group / hydroxyl group of polydimethylsiloxane is 1.5.
It is preferably from 10.0 to 10.0. This molar ratio is 1.5
In the case of the above, there is no fear of gelling of the silicone rubber layer solution. On the other hand, in the case of 10.0 or less, no embrittlement of the physical properties of the rubber and no adverse effect on the scratch resistance of the printing plate will be caused.

Acetic acid, propionic acid,
Organic carboxylic acids such as maleic acid; acids such as toluenesulfonic acid and boric acid; alkalis such as potassium hydroxide, sodium hydroxide and lithium hydroxide; amines; metal alkoxides such as titanium tetrapropoxide and titanium tetrabutoxide; and iron Metal diketenates such as acetylacetonate and titanium acetylacetonate dipropoxide, and organic acid salts of metals can be given. Among them, it is preferable to add an organic acid salt of a metal, particularly preferably an organic acid salt of a metal selected from tin, lead, zinc, iron, cobalt, calcium, and manganese. Specific examples of such compounds include dibutyltin diacetate, dibutyltin dioctate, dibutyltin dilaurate, zinc octylate, and iron octylate. The amount of such a curing catalyst is 0.01 to 20 wt% as a solid content in the silicone rubber layer,
More preferably, it is 0.1 to 10% by weight. When the amount of the catalyst to be added is 0.01 wt% or more, the curing of the silicone rubber layer does not become insufficient, and there is no problem in the adhesiveness to the heat-sensitive layer. On the other hand, 20wt%
The following will not adversely affect the pot life of the silicone rubber layer solution.

Further, in addition to these compositions, a known filler such as silica and a known silane coupling agent may be contained for the purpose of improving rubber strength. Thickness of the silicone rubber layer is preferably 0.5 to 20 g / m ^2, more preferably 1 to 4 g / m ^2. 0.5 film thickness
g / m ² or more, the ink repellency, scratch resistance and printing durability of the printing plate do not tend to be reduced, and are reduced to 20 g / m 2.
If it is ² or less, not only is it advantageous from an economic point of view, but there is no problem that developability and ink mileage deteriorate.

The direct drawing type lithographic printing plate precursor of the invention may be laminated with a protective film or formed with a protective layer for the purpose of protecting the ink repellent layer. Examples of the protective film include a polyester film, a polypropylene film, a polyvinyl alcohol film, a saponified ethylene vinyl acetate copolymer film, and a polyvinylidene chloride film. The thus obtained direct drawing type lithographic printing plate precursor is exposed imagewise with a laser beam after the protective film is peeled off or from above the protective film.

From the thus obtained direct drawing type lithographic printing plate precursor having at least a heat-sensitive layer and an ink repellent layer on the substrate in this order, a decomposition product is generated on the surface of the heat-sensitive layer by the action of laser irradiation. By promoting internal curing,
Direct-drawing lithographic printing plates can be manufactured.

As the laser light source used in the plate-making exposure step of the direct drawing type lithographic printing plate precursor according to the present invention, one having an emission wavelength range of 300 nm to 1500 nm is used. A semiconductor laser or a YAG laser having an emission wavelength region is preferably used. Specifically, a laser beam having a wavelength of 780 nm, 830 nm, or 1064 nm is preferably used for plate making from the viewpoint of handling of the plate material in a bright room.

In the present invention, a decomposition product is generated on the surface of the heat-sensitive layer by laser irradiation, and the inside of the heat-sensitive layer is further cured by laser irradiation. The original plate after laser irradiation is developed by friction treatment in the presence or absence of water or an organic solvent. The rubbing treatment is performed by wiping the plate surface with a non-woven fabric, absorbent cotton, cloth, sponge, or the like impregnated with a developer, or by rubbing the plate surface with a rotating brush while showering with tap water after pre-treating the plate surface with the following developer. be able to.

Examples of the developing solution used in the development treatment include water and water obtained by adding a surfactant to water,
Further, a polar solvent such as alcohol, ketone, ester, or carboxylic acid is added to water, or at least one polar solvent is added to a solvent composed of at least one of aliphatic hydrocarbons and aromatic hydrocarbons. What did
Alternatively, a polar solvent is used alone. It is also preferable to add a known surfactant to the developer composition. Further, an alkali agent such as sodium carbonate, monoethanolamine, diethanolamine, diglycolamine, monoglycolamine, sodium silicate, potassium hydroxide, sodium borate and the like can be added. Among these, water or a mixture of water and a surfactant is preferable.

[0063]

The present invention will be described below in more detail with reference to examples.

Example 1 A solution having the following composition was applied on a degreased aluminum plate having a thickness of 0.24 mm using a slit die coater, dried at 200 ° C. for 2 minutes, and dried at 3 g / g.
An m2 primer layer was provided. <Primer 1> (a) Epoxy / phenol resin “Cancoat” 90T
-25-3094 (manufactured by Kansai Paint Co., Ltd.): 15 parts by weight (b) Dimethylformamide: 85 parts by weight A solution having the following composition was applied on this primer layer by a slit die coater, and 130 ° C. × 30 seconds. After drying, a heat-sensitive layer of 1 g / m ² was provided. <Thermal Sensitive Layer 1> (a) “KAYASORB” IR-820B (dye (light-to-heat conversion material), manufactured by Nippon Kayaku Co., Ltd.): 10 parts by weight (b) “Nasem Titanium” (manufactured by Nippon Chemical Industry Co., Ltd., -N-butoxide (bis-2,4-pentanedionate)): 10 parts by weight (c) "Sumilite resin" PR50622 (phenol novolak resin, manufactured by Sumitomo Durez Co., Ltd.): 70 parts by weight (d) "Samprene""T1331D (polyurethane, manufactured by Sanyo Chemical Industry Co., Ltd.): 10 parts by weight (as solid content) (e)" Solvent Orange "502A (the compound 1)
(Ciba Specialty Chemicals Co., Ltd.): 1
0 parts by weight “Solvent Orange” 502A is a dye that is soluble in a solvent and changes its color by laser irradiation.
Decomposition starts at about ° C, and almost all decomposes at 150 ° C to 200 ° C. Decomposition produces carbon dioxide and 2,2-dimethylbutane. Generates carbon dioxide and 2,2-dimethylbutane. (F) Tetrahydrofuran: 550 parts by weight (g) Dimethylformamide: 350 parts by weight
The drying condition was 120 ° C. × 2 minutes, and the coating was performed with a slit die coater. <Silicone rubber layer 1> (a) α, ω-divinylpolydimethylsiloxane (molecular weight: about 60,000): 100 parts by weight (b) HMS-501 (manufactured by Chisso Corporation at both ends methyl (methylhydrogensiloxane) ( Dimethylsiloxane) copolymer SiH group number / molecular weight = 0.69 mol /
g): 7 parts by weight (c) "BY24-808" (manufactured by Toray Dow Corning Silicone Co., Ltd., reaction inhibitor): 3 parts by weight (d) "SRX-212" (manufactured by Toray Dow Corning Silicone Co., Ltd.) Platinum catalyst): 5 parts by weight (e) Vinyl tri (methyl ethyl ketoxime) silane: 3 parts by weight (f) "ISOPAR" E (manufactured by Esso Chemical Co., Ltd.): 10
00 parts by weight

An 8 μm thick polypropylene film “Trefane” BO was added to the laminate obtained as described above.
(Manufactured by Toray Industries, Inc.) was laminated using a calendar roller to obtain a direct-drawing waterless planographic printing plate precursor.

Thereafter, this printing plate precursor was transferred to a plate making machine “FX4
00-AP "(manufactured by Toray Engineering Co., Ltd.) and a semiconductor laser (wavelength: 830 nm, beam diameter: 20 mm).
exposure time of 10 μs and irradiation energy of 20 μm).
Exposure was performed at 0 mJ / cm ² .

In the printing plate after the exposure, the heat-sensitive layer in the laser-irradiated portion was discolored from yellow-green to orange, and showed good printing properties.

Subsequently, an automatic developing apparatus "TWL-650"
When development was carried out by Toray Industries, Inc., a negative waterless lithographic plate was obtained in which the silicone rubber layer in the portion irradiated with the laser beam was removed.

At the time of development, the pretreatment liquid is "NP-1"
(Pretreatment liquid for waterless lithographic negative mold, manufactured by Toray Industries, Inc.), and water as a developer.

Further, the obtained printing plate was attached to a sheet-fed offset printing machine “HAMADA RS34L” (manufactured by Hamada Printing Machinery Co., Ltd.), and “Dryocolor NSI” indigo (manufactured by Dainippon Ink and Chemicals, Inc.) When printing was performed on high-quality paper (62.5 kg / chrysanthemum) using a waterless lithographic ink, a printed matter faithfully reproducing an image from 1 to 99% was obtained.

Comparative Example 1 A printing plate precursor was prepared in exactly the same manner as in Example 1 except that (e) “Solvent Orange” 502A was omitted from the composition of the heat-sensitive layer. Could not be confirmed.

However, when development and print evaluation were performed in the same manner as in Example 1, a printed matter in which an image was faithfully reproduced from 1 to 99% as in Example 1 could be obtained.

Example 2 The composition of the heat-sensitive layer in Example 1 (e) “Solvent Orange” 502A was replaced with (e ′) “Solv
When a printing plate precursor was prepared in exactly the same manner except that ent Yellow "765A was used, the laser-irradiated portion of the plate after laser irradiation changed color from yellow-green to yellow-pink,
A printing plate having good print-out properties was obtained. (E ′) “Solvent Yellow” 765A (Compound 2)
(Ciba Specialty Chemicals Co., Ltd.): 1
0 parts by weight “Solvent Yellow” 765A is a dye which is soluble in a solvent and changes its color upon laser irradiation.
Decomposition starts at about ° C, and almost all decomposes at 150 ° C to 200 ° C. Decomposition produces carbon dioxide and 2,2-dimethylbutane.

Further, development and printing evaluation were performed in the same manner as in Example 1. As in Example 1, a printed matter in which an image was faithfully reproduced from 1 to 99% was obtained.

[0075]

According to the present invention, a negative direct drawing type lithographic printing plate having a good printing property can be obtained.

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Claims (3)

[Claims] 1. A direct drawing type lithographic printing plate precursor having at least a heat-sensitive layer on a substrate, wherein the heat-sensitive layer contains a dye that is soluble in a solvent and changes color by laser irradiation. A lithographic printing plate precursor directly drawn. 2. The lithographic printing plate precursor according to claim 1, wherein the dye generates gas by the action of a laser. 3. The decomposition temperature of the dye is 100 to 500 ° C.
The direct-lithographic printing plate precursor according to claim 1 or 2, wherein